Parameter identification of rockfall protection barrier components through an inverse formulation

Rockfall barriers are key protection systems in mountainous regions worldwide. They are designed to intercept and capture falling rocks. Most systems are composed of flexible steel wire-nets connected to wire-rope cables which are in turn attached to steel posts and anchored to the ground. Additional energy dissipating devices can be connected to the cables to enhance the performance of the barriers. The composition and geometrical arrangement of wires forming net components and cables are a severe limitation to realistic finite element (FE) modeling of rockfall barriers. Detailed models are computationally expensive. Therefore, macroscopic models reflecting the system behavior on a coarser scale, i.e., the global behavior, need to be derived. In this work, macroscopic FE models pertaining to the modeling of the wire-ring net and the spiral cables have been developed and investigated. Material plasticity, damage initiation and ductile damage are taken into account. The non-linear force displacement response obtained in laboratory tests has been successfully reproduced by introducing additional parameters. An inverse optimization process based on the multi-island genetic algorithm is used for the determination of model parameters. The developed numerical approach succeeds in modeling rockfall barrier connections in a manner that is more refined than previous attempts, yet of low computational expense. The accuracy of this approach is verified by the match between simulation and test results of a full scale rockfall barrier prototype that was tested according to the ETAG027 standard.